SUMMARY: high Ierrs on SUN3/50

Recap: SUN 3/50 slowing down to a crawl. "netstat -i" shows
very high number of Ierrs (input packet errors) in the Ether
interface. OS v3.5. No other machines in the net are
apparently affected. Checking cables, moving machine
physically and rebooting has no effect.

Didn't want to do that right away. We didn't have a maintenance
contract anymore and didn't want to spend money on obsolete
technology.

>
>From: daryl@oceanus.mitre.org (Daryl Crandall)
>
> loose BNC connector somewhere down the cable?
>
> loose drop-cable from a SPARCstation to it's tranceiver?
>
> rodent bites in the cable behind a wall?
>
> a new workstation or PC on the net?
>
> a new gateway or router on the net?
>
> less than 3' between workstations on the cable?
>
> malfunctioning leg of a repeater?
>
> are the switch settings inside the 3/50 firmly selected to either
> thin or thicknet connector? Vibration may have jiggled a switch.
> (unlikely, but it's happened to me)
>
> Are all chips firmly seated in the 3/50? Vibration or corrosion may
> have produced an intermittent connection. May be a good opportunity
> to open the case and carefully clean the insides, and rock each
> socketed chip slightly to re-seat it. (Watch out for static.)
>

All good suggestions. However, none of them produced any
results in our case.

>
>From: mis@seiden.com (Mark Seiden)
>
>cmon, be a scientist. or pretend you're one:
>1. try swapping the system unit with one on a different ethernet tap
>to figure out if it's the network segment or the workstation.
>2. try switching to external transceiver -- you may just have a bad
>onboard thinnet transceiver.
>
>mark seiden, mis@seiden.com, 1-(203) 329 2722 (voice), 1-(203) 322 1566 (fax)
>
>From: etnibsd!vsh@uunet.UU.NET (Steve Harris)
> ... ditto ...
>Steve Harris - Eaton Corp. - Beverly, MA - uunet!etnibsd!vsh
>
Concise, to the point and .... produced a result! Wish I had
thought of it. Indeed, with an external transceiver, the
problem went away. This indicated the on-board transceiver.
>
>From: kjl@ray.fi (Kari J Leino)
>
>We had similar problems with three of our SUN 3/50 machines. The only thing
>that seemed to help was replacing the Ethernet buffers on the CPU board.
>There are two AMD chips on the board, AM7992BDC and AM7996DC. Replacing
>these circuits (they are on sockets) helped with two of the failing machines,
>the third we had already decided to upgrade to a SparcStation IPC, so we
>did not try to fix it.
>
>Kari J. Leino kjl@ray.fi>Raha-automaattiyhdistys p. 3580-4370616
>Turuntie 42, 02600 ESPOO f. 3580-4370647
>Finland
>
BINGO! Since they were so cheap, we ordered them from a
local electronic firm (apprx. $50 for both). So far, it
appears to have solved the problem. The SUN is back on it
internal transceiver with no sign of errors (yet).

Thanks to all of the aforemention and to those whom I had
extended discussions with. Also, a note to other sys admins:

Keep an eye on the length of a growing network. We finally tallied
up our cable segments and found out we are at over 400m on a 10base2
(thinnet coax) network!! The recommended max is 185m. Everything still
works well but we've invested in a repeater and are going to re-arrange our
topography. This isn't related to the SUN 3 problem except it
was the catalyst for our new-found interest in net optimization.